U.S. patent application number 11/920114 was filed with the patent office on 2009-04-23 for engine measurement device.
This patent application is currently assigned to A&D Company, Ltd.. Invention is credited to Mitsuharu Sugita.
Application Number | 20090100919 11/920114 |
Document ID | / |
Family ID | 37396252 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090100919 |
Kind Code |
A1 |
Sugita; Mitsuharu |
April 23, 2009 |
Engine Measurement Device
Abstract
An engine measurement device includes a detector for measuring
individual pieces of time series data containing at least a speed
and output torque of an engine in a transient state while the
engine is being run in combustion by control of an engine control
unit, a torque operation unit for calculating the engine torque on
the basis of the time series data of the engine speed and the
output torque, and a model operation unit for modeling the engine
torque as functions of the engine speed and a fuel injection time.
This model is used to calculate both a fuel torque generated by the
combustion run of the engine and a mechanical loss torque or the
difference between the engine torque and the fuel torque.
Inventors: |
Sugita; Mitsuharu; (Saitama,
JP) |
Correspondence
Address: |
JORDAN AND HAMBURG LLP
122 EAST 42ND STREET, SUITE 4000
NEW YORK
NY
10168
US
|
Assignee: |
A&D Company, Ltd.
Toshima-ku, Tokyo
JP
|
Family ID: |
37396252 |
Appl. No.: |
11/920114 |
Filed: |
May 9, 2005 |
PCT Filed: |
May 9, 2005 |
PCT NO: |
PCT/JP2005/008445 |
371 Date: |
November 8, 2007 |
Current U.S.
Class: |
73/114.15 ;
73/114.49 |
Current CPC
Class: |
F02D 41/1497 20130101;
G01L 5/133 20130101; G01L 5/26 20130101; G01M 15/044 20130101 |
Class at
Publication: |
73/114.15 ;
73/114.49 |
International
Class: |
G01L 3/26 20060101
G01L003/26; G01M 15/00 20060101 G01M015/00 |
Claims
1. An engine measurement device for measuring engine performance by
bench testing an automobile engine having a load connected to said
engine, said engine measurement device comprising: an engine
control unit for controlling a fuel injection timing of said
engine; a detector for measuring time series data that include at
least an engine speed of said engine and an axial torque detected
between said engine and a load in a transient state, in a state in
which said engine is combustion-driven by the control of said
engine control unit; a torque computation unit for computing an
engine torque that is an actual drive force of said engine on a
basis of the time series data of said engine speed and axial
torque; and a model computation unit for modeling said engine
torque using a model and engine parameters including said engine
speed, and said fuel injection timing; wherein a fuel torque
generated by the combustion driving of said engine, and a
mechanical loss torque that is a difference between said engine
torque and said fuel torque are calculated from said model.
2. An engine measurement device for measuring engine performance by
bench testing an automobile engine having an external driving means
connected to said engine, said engine measurement device
comprising: an engine control unit for controlling a throttle
travel of said engine; an external driving means control unit for
controlling said external driving means; a detector for measuring
time series data that include at least an engine speed of said
engine and an axial torque detected between said engine and the
external driving means in a transient state, in a non-combustion
drive state in which said external driving means is driven by the
control of said engine control unit and the external driving means
control unit; a torque computation unit for computing an engine
torque that is an actual drive force of said engine as a mechanical
loss torque that occurs during said non-combustion driving, on a
basis of the time series data of said engine speed and axial
torque; and a model computation unit for modeling said mechanical
loss torque using a model and engine parameters including said
engine speed, an engine oil temperature, and an intake air
quantity; wherein said mechanical loss torque is computed from said
model for each of said engine parameters.
3. The engine measurement device according to claim 1, wherein said
model is a function of said engine parameters.
4. The engine measurement device according to claim 1, wherein said
engine measurement device comprises a display unit for displaying
said computed engine torque, mechanical loss torque, fuel torque,
and any two or more of said engine parameters.
5. The engine measurement device according to claim 1, wherein said
torque computation unit computes said engine torque by performing
computational processing that includes time differentiation of the
time series data of said engine speed.
6. The engine measurement device according to claim 1, wherein:
said torque computation unit comprises a filter processing unit for
removing the effects of a moment of inertia that is included in
said time series data; and said filter processing unit performs
frequency analysis of said time series data to separate the time
series data into a low-frequency component and a high-frequency
component, and removes the high-frequency component using a
low-pass filter.
7. The engine measurement device according to claim 1, wherein the
model computation unit determines constants Kf.sub.1, Kf.sub.2,
Km.sub.1, and Km.sub.2 so as to conform to the function: Engine
torque
T.sub.e=(Kf.sub.1.times.(FT).sup.2+Kf.sub.2.times.(FT))+(Km.sub.1.times.(-
N)+Km.sub.2) wherein N is the engine speed and FT is fuel injection
timing and are engine parameters.
8. The engine measurement device according to claim 7, said engine
measurement device wherein: the mechanical loss torque is T.sub.m
and T.sub.m=-(Km.sub.1.times.(N)+Km.sub.2).
9. The engine measurement device according to claim 2, wherein the
model computation unit indicates the engine speed as N as an engine
parameter, and indicates the mechanical loss torque as T.sub.mm as
a primary approximation or secondary approximation of the engine
speed N.
10-12. (canceled)
13. The engine measurement device according to claim 2, wherein
said model is a function of said engine parameters.
14. The engine measurement device according to claim 2, wherein
said engine measurement device comprises a display unit for
displaying said computed engine torque, mechanical loss torque,
fuel torque, and any two or more of said engine parameters.
15. The engine measurement device according to claim 2, wherein
said torque computation unit computes said engine torque by
performing computational processing that includes time
differentiation of the time series data of said engine speed.
16. The engine measurement device according to claim 2, wherein:
said torque computation unit comprises a filter processing unit for
removing the effects of a moment of inertia that is included in
said time series data; and said filter processing unit performs
frequency analysis of said time series data to separate the time
series data into a low-frequency component and a high-frequency
component, and removes the high-frequency component using a
low-pass filter.
17. An engine measurement device for measuring engine performance
by bench testing an automobile engine having a load connected to
said engine and an external driving means connected to said engine,
said engine measurement device comprising: a first engine control
unit for controlling a fuel injection timing of said engine; a
second engine control unit for controlling a throttle travel of
said engine; an external driving means control unit for controlling
said external driving means; a detector for measuring time series
data that include at least: an engine speed of said engine; an
axial torque detected between said engine and a load in a transient
state, in a state in which said engine is combustion-driven by the
control of said engine control unit; and an axial torque detected
between said engine and the external driving means in a transient
state, in a non-combustion drive state in which said external
driving means is driven by the control of said engine control unit
and the external driving means control unit; a first torque
computation unit for computing a first engine torque on a basis of
the time series data of said engine speed and axial torque; a
second torque computation unit for computing an second engine
torque as a mechanical loss torque that occurs during said
non-combustion driving, on a basis of the time series data of said
engine speed and axial torque; a first model computation unit for
modeling said first engine torque using a first model and engine
parameters including said engine speed, and said fuel injection
timing, wherein a fuel torque generated by the combustion driving
of said engine, and a first mechanical loss torque T.sub.m that is
a difference between said first engine torque and said fuel torque
are calculated from said model; a second model computation unit for
modeling said mechanical loss torque using a second model and
engine parameters including said engine speed, an engine oil
temperature, and an intake air quantity, wherein a second
mechanical loss torque T.sub.mm is computed from said second model
for each of said engine parameters; and a comparing unit for
comparing the first mechanical loss torque T.sub.m computed by the
first model computation unit and the second mechanical loss torque
T.sub.mm computed by the second model computation unit to verify
validity and consistency of the first and second mechanical loss
torques.
18. The engine measurement device according to claim 17, wherein:
the first mechanical loss torque T.sub.m and the second mechanical
loss torque T.sub.mm are each modeled as primary approximations of
the engine speed N; and the validity and consistency of the first
mechanical loss torque T.sub.m and the second mechanical loss
torque T.sub.mm are verified by comparing the engine speed N
coefficients with each other.
19. The engine measurement device according to claim 18, wherein a
mechanical loss torque due to combustion in said engine is computed
by subtracting said second mechanical loss torque T.sub.mm from the
first mechanical loss torque T.sub.m.
20. The engine measurement device according to claim 17, wherein a
mechanical loss torque due to combustion in said engine is computed
by subtracting said second mechanical loss torque T.sub.mm from the
first mechanical loss torque T.sub.m.
Description
TECHNICAL FIELD
[0001] The present invention relates to an engine measurement
device for measuring mechanical loss in an automobile engine.
BACKGROUND ART
[0002] In order to evaluate whether a developed/manufactured
automobile engine is providing the prescribed performance, bench
testing has recently been performed by placing the engine to be
tested on a platform (engine bench), connecting a dynamometer to
the output shaft of the engine via a torque meter and an engine
speed meter, and driving the dynamometer to measure/evaluate the
performance of the engine unit.
[0003] Examples of applications regarding this bench testing system
include (1) an "engine bench system (Japanese Laid-open Patent
Application No. 2003-207424)" in which an engine-dynamo system is
modeled as an inertial system; (2) an "engine bench system
(Japanese Laid-open Patent Application No. 2003-207422)" in which a
mechanical parameters of the inertial system of an engine-dynamo
control system is used to model a control system; (3) an
"automobile engine testing device (Japanese Patent No. 3489241)" in
which an actuator is linked to the throttle valve of an engine via
a wire, and a model is created for a control object from an
actuator position command up until an estimated torque is obtained;
and other examples.
[0004] Measurement of the mechanical loss of an engine in an
evaluation of the performance of the engine is desired both for
enhancing fuel consumption and for performing highly precise ECU
control.
[0005] The term "mechanical loss" refers to the difference between
the fuel torque (input) that is generated by combustion driving of
the engine, and the engine torque (output) that is the force that
actually drives the engine, and is a generic term for frictional
loss between the cylinders and the pistons and piston rings,
frictional loss from the crankshaft, camshaft, and other bearings,
frictional loss between cams and cam followers, drive loss and
other frictional loss in the alternator, pumps, distributor, and
other auxiliary machinery, engine pump loss (pumping loss) and
thermal loss that cannot be separated for measurement, and other
torques that do not contribute to combustion driving of the
engine.
[0006] The mechanical loss of an engine has therefore been measured
in the past using the system described in Patent Document 1. In the
mechanical loss torque measurement system described in Patent
Document 1, an engine 20 is connected to a motor 30 (dynamometer),
and the torque of the motor 30 is measured multiple times under the
same conditions (at a constant engine speed and engine oil
temperature) without inducing combustion in the engine. Testing
according to a method in which the torque is measured with the
engine speed and other conditions held constant (steady state) is
generally referred to as steady-state testing.
[0007] Patent Documents 2 and 3 also disclose devices for
calculating mechanical loss or engine torque through steady-state
testing.
[0008] However, such measurement systems have the technical
drawbacks described below.
[0009] Patent Document 1: Japanese Laid-open Patent Application No.
2002-267552
[0010] Patent Document 2: Japanese Laid-open Patent Application No.
2002-206453
[0011] Patent Document 3: Japanese Patent No. 3489241
[0012] In the measurement systems disclosed in Patent Documents 1
through 3, measurement must be performed in a steady state in which
the engine speed and other conditions are constant.
[0013] Not only in engine speed, but in almost all physical
phenomena, the steady state is generally achieved after a transient
state (a state in which values cannot stabilize at a constant
level, and cycle with a certain amplitude), and a time of several
tens of seconds is required for the engine speed to settle into a
steady state even in the case of engine torque measurement.
[0014] Consequently, a period of several days is required to obtain
all the torque data for each engine speed/throttle travel that are
necessary to evaluate the engine performance. Furthermore, the
items evaluated for engine performance are not limited to engine
torque or mechanical loss, and several hundred aspects are tested.
A method is therefore needed for speeding the acquisition of even
one of these items of measurement data.
[0015] The present invention was developed in view of such
drawbacks as the foregoing, and an object of the present invention
is to provide an engine measurement device for calculating the
mechanical loss of an engine in a short time during the period of
the transient state that occurs before the items of data stabilize
into a steady state, without using the conventional steady-state
testing method.
[0016] The technological background that makes the present
invention possible includes significant progress in semiconductor
devices used for digital processing that enable multi-channel
measurement data to be acquired at high speed and high resolution
and stored as time-axis synchronized signals, and that enable
removal of high-frequency components by a low-pass filter,
time-axis compensation/inverse transfer function compensation of
measurement time delays between channels, and other processing; and
the application of these semiconductor devices in transient
measurement.
Means Used to Solve the Above-Mentioned Problems
[0017] The engine measurement device of the present invention for
achieving the abovementioned objects is an engine measurement
device for measuring engine performance by bench testing that is
performed by an automobile engine and a load connected to the
engine, wherein the engine measurement device is configured so that
the engine measurement device comprises an engine control unit for
controlling a fuel injection timing of the engine; a detector for
measuring time series data that include at least a speed of the
engine and an axial torque detected between the engine and a load
in a transient state, in a state in which the engine is
combustion-driven by the control of the engine control unit; a
torque computation unit for computing an engine torque that is the
actual drive force of the engine on the basis of the time series
data of the engine speed and axial torque; and a model computation
unit for modeling the engine torque using the engine speed, the
fuel injection timing, and other engine parameters; wherein a fuel
torque generated by the combustion driving of the engine, and a
mechanical loss torque that is the difference between the engine
torque and the fuel torque are calculated from the model.
[0018] Such a configuration makes it possible to calculate the
mechanical loss of the engine in a short time during the period of
the transient state before the measurement data stabilizes into a
steady state, without the use of the conventional steady-state
testing method.
[0019] In the past, since testing to calculate the mechanical loss
torque was performed without combustion-driving of the engine, it
was impossible to measure the fuel torque as an input factor, and
the mechanical loss that was calculated during combustion driving
of the engine had insufficient accuracy. However, according to the
present invention, the engine torque during combustion driving of
the engine is computed as a separate fuel torque and a mechanical
loss torque, and the engine torque can also be computed in a short
time using transient data. The engine torque can therefore be
useful for enhancing the accuracy of ECU control for enhancing fuel
consumption, and for other aspects of engine control.
[0020] In an engine measurement device for measuring engine
performance by bench testing that is performed by an automobile
engine and an external driving means connected to the engine, the
engine measurement device is configured so that the engine
measurement device comprises an engine control unit for controlling
the throttle travel of the engine; an external driving means
control unit for controlling the external driving means; a detector
for measuring time series data that include at least a speed of the
engine and an axial torque detected between the engine and the
external driving means in a transient state, in a non-combustion
drive state in which the external driving means is driven by the
control of the engine control unit and the external driving means
control unit; a torque computation unit for computing an engine
torque that is the actual drive force of the engine as a mechanical
loss torque that occurs during the non-combustion driving, on the
basis of the time series data of the engine speed and axial torque;
and a model computation unit for modeling the mechanical loss
torque using the engine speed, an engine oil temperature, an intake
air quantity, and other engine parameters; wherein the mechanical
loss torque is computed from the model for each of the engine
parameters.
[0021] Such a configuration makes it possible to calculate the
mechanical loss of the engine in a short time during the period of
the transient state before the measurement data stabilizes into a
steady state, without the use of the conventional steady-state
testing method.
[0022] Since the mechanical loss torque can be computed separately
for each engine parameter, the engine parameter that is taken into
account during modeling of the mechanical loss can be arbitrarily
selected in accordance with the purpose of the testing/evaluation,
and the flexibility of the testing/evaluation is improved.
[0023] The model may be a function of the engine parameters.
[0024] The mechanical loss torque of each engine parameter can
easily be computed by functional modeling.
[0025] The engine measurement device may also be provided with a
display unit for displaying the computed engine torque, mechanical
loss torque, fuel torque, and any two or more of the engine
parameters.
[0026] According to such a configuration, the torques or engine
parameter functions can be visually assessed at a glance, thereby
contributing to rapid evaluation of engine performance, and
enhanced accuracy of ECU control.
[0027] The torque computation unit may also compute the engine
torque by performing computational processing that includes time
differentiation of the time series data of the engine speed.
[0028] According to such a configuration, the engine torque is
computed from transient data, and the computation time is therefore
significantly reduced in comparison with the conventional engine
measurement device in which the engine torque was computed after
waiting for the engine speed to stabilize into a steady state.
[0029] The torque computation unit may comprise a filter processing
unit for removing the effects of a moment of inertia that is
included in the time series data, wherein the filter processing
unit performs frequency analysis of the time series data to
separate the time series data into a low-frequency component and a
high-frequency component, and removes the high-frequency component
using a low-pass filter.
[0030] When the high-frequency component that is superposed on the
transient data used in the present invention is merely averaged,
the high-frequency component is cancelled out to zero, the data are
altered from the data that were to be used in the original
evaluation, and a proper evaluation can no longer be performed. A
method for separating the transient data into low frequencies and
high frequencies and removing unnecessary components is therefore
an essential technique for analysis and processing of transient
data.
[0031] The model computation unit may determine constants Kf.sub.1,
Kf.sub.2, Km.sub.1, and Km.sub.2 so as to conform to the
function:
Engine torque
T.sub.e=(Kf.sub.1.times.(FT).sup.2+Kf.sub.2.times.(FT))+(Km.sub.1.times.(-
N)+Km.sub.2)
[0032] wherein the engine speed N and the fuel injection timing FT
are engine parameters.
[0033] The model computation unit according to the first aspect may
thus model the engine torque using a function.
[0034] The following function may also be used: Mechanical loss
torque T.sub.m=-(Km.sub.1.times.(N)+Km.sub.2).
[0035] As previously mentioned, by modeling the engine torque as a
function of the engine speed and the fuel injection timing, the
factor that depends on the engine speed can be considered as the
mechanical loss torque.
[0036] The model computation unit may indicate the engine speed N
as an engine parameter, and indicates a mechanical loss torque
T.sub.mm as a primary approximation or secondary approximation of
the engine speed N.
[0037] The model computation unit according to the second aspect
thus models the engine torque as a function of the engine speed,
and the function model can thereby be directly considered as the
mechanical loss torque.
[0038] The model of the mechanical loss torque T.sub.m computed by
the engine measurement device according to the first aspect may be
compared with the model of the mechanical loss torque T.sub.mm
computed by the engine measurement device according to the second
aspect to verify the validity and consistency of the mechanical
loss torques.
[0039] Specifically, the mechanical loss torque T.sub.m and the
mechanical loss torque T.sub.mm may each be modeled as primary
approximations of the engine speed N, and the validity and
consistency of the mechanical loss torques may be verified by
comparing the engine speed N coefficients with each other.
[0040] The mechanical loss torques T.sub.m and T.sub.mm differ from
each other according to the testing conditions as to whether
combustion is induced in the engine, but the validity and
consistency of the mechanical loss torques T.sub.m and T.sub.mm can
be verified through comparison of the mechanical loss torques with
each other. Since T.sub.m and T.sub.mm can be treated as data in
the same dimension, different mechanical loss data resulting from
different tests can be appropriately combined and used for engine
analysis.
[0041] The mechanical loss torque due to combustion in the engine
may be computed by subtracting the mechanical loss torque T.sub.mm
from the mechanical loss torque T.sub.m.
[0042] Since a mechanical loss torque due to combustion, as well as
a mechanical loss torque due to machine components, and all other
types of mechanical loss are included in the mechanical loss torque
T.sub.m, a consistent mechanical loss torque T.sub.m and mechanical
loss torque T.sub.mm can be used to extract only the mechanical
loss torque that is caused by combustion, which could not be
measured in the past.
Effect of the Invention
[0043] The engine measurement device of the present invention makes
it possible to calculate the mechanical loss of an engine in a
short time during the period of the transient state that occurs
before the items of measurement data stabilize into a steady state,
without using the conventional steady-state testing method.
[0044] In the past, since testing to calculate the mechanical loss
torque was performed without combustion-driving of the engine, it
was impossible to measure the fuel torque as an input factor, and
the mechanical loss that was calculated during combustion driving
of the engine had insufficient accuracy. However, according to the
present invention, the engine torque during combustion driving of
the engine is computed as a separate fuel torque and a mechanical
loss torque, and the engine torque can also be computed in a short
time using transient data. The engine torque can therefore be
useful for enhancing the accuracy of ECU control for enhancing fuel
consumption, and for other aspects of engine control.
[0045] When the mechanical loss is calculated during non-combustion
driving, since the mechanical loss torque can be computed
separately for each engine parameter, the engine parameter that is
taken into account during modeling of the mechanical loss can be
arbitrarily selected in accordance with the purpose of the
testing/evaluation, and the flexibility of the testing/evaluation
is improved.
BEST MODE FOR CARRYING OUT THE INVENTION
[0046] Preferred embodiments of the present invention will be
described in detail hereinafter based on the accompanying drawings.
FIG. 1 is a diagram showing the general connection configuration of
the engine measurement device 1 of the present example, wherein the
engine measurement device 1 is provided with an automobile engine
10 as the testing subject, a dynamometer 12 that is connected to
the engine 10, and a stand (engine bench) 14 for fixing the engine
10 and the dynamometer 12.
[0047] Methods of testing that use the engine measurement device 1
include firing testing for measuring engine performance in a state
in which fuel is fed to the engine 10 to cause combustion driving
in the engine 10, and motoring testing in which engine performance
is measured in a non-combustion driving state of the engine 10
without feeding/combusting fuel, i.e., a state in which the
dynamometer 12 is driven. However, a case will be described in the
present example in which the engine measurement device 1 is first
used in firing testing.
[0048] The engine measurement device 1 is used in bench testing for
simple measurement/evaluation of the performance of the engine 10
without connecting actual components (transmission, tires, and the
like) other than the engine 10.
[0049] In the present example, one end of a torque transmission
shaft 16 is connected to the output shaft of the engine 10 via a
universal joint 16a or other connecting member, an engine speed
detector (tachymeter), a torque meter, or other type of detector 2
is connected to the other end of the torque transmission shaft 16,
and a dynamometer 12 is connected via the detector 2.
[0050] A low-inertia dynamometer is used as the dynamometer 12 of
the present example so as to enable a stable output to be obtained
from the detector 2 according to each engine speed even when a
sudden change in engine speed occurs from low-speed rotation of the
engine 10 to high-speed rotation at maximum output.
[0051] In the present example, the torque is detected in the
detector 2 that is placed between the torque transmission shaft 16
and the dynamometer 12, but it is also possible to detect the
torque from the output of the dynamometer 12. Besides the detector
2, a clutch, a transmission, and various types of linkages and the
like may also be inserted into the torque transmission shaft 16
according to the purpose of the bench testing.
[0052] Since the dynamometer 12 used in the present example is a
low-inertia dynamometer, and the load torque detected by the
dynamometer 12 and the axial torque T.sub.d detected by the
detector 2 are essentially the same, the load torque and the axial
torque T.sub.d mentioned hereinafter are synonymous. In the present
specification, the load torque detected by the dynamometer 12 is
included in the axial torque T.sub.d that is detected between the
engine 10 and the dynamometer 12.
[0053] Furthermore, the engine measurement device 1 is provided
with an engine control unit 3, a central control unit 5, a signal
processing unit 6, and a display unit 7.
[0054] The engine control unit 3 is connected to the engine 10, and
is a means of controlling the throttle travel S and the fuel
injection timing FT of the engine 10 during the firing testing of
the present example. The engine control unit 3 may also be included
within the engine ECU.
[0055] In the case of firing testing, the engine control unit 3
provides a prescribed fuel injection timing FT to the engine 10,
whereby the engine 10 performs combustion, the force of the
exploding fuel in an internal cylinder is received by a piston, and
the vertical movement of the piston is transmitted to the
dynamometer 12 via the torque transmission shaft 16 and converted
to rotational movement of the dynamometer 12. In other words, the
engine speed N of the engine 10 is obtained through the control of
the fuel injection timing FT by the engine control unit 3. The
engine speed N can be detected by the detector 2, as well as by a
tachymeter (not shown) that is mounted to the engine 10 or the
dynamometer 12. The dynamometer 12 supplies the load during the
firing testing of the present example.
[0056] The central control unit 5 is a means of controlling the
engine control unit 3, the signal processing unit 6 described
hereinafter, and the display unit 7. The central control unit 5 may
operate based on an instruction from an operation input unit not
shown in the drawing, for example. The central control unit 5 and
the engine control unit 3 may also be an ECU.
[0057] The central control unit 5 of the present example controls
the engine control unit 3 in the control process of the engine 10
so that at least two types of time series data that include time
series data of the engine speed N in the non-constant transient
state, and the axial torque T.sub.d that varies during the period
of the transient state are measured from the detector 2.
[0058] The signal processing unit 6 is provided with a measurement
unit 60, memory 62, a torque computation unit 64, and a model
computation unit 66, and operates based on the instruction of the
central control unit 5, as shown in detail in FIG. 1. A control
unit for controlling the signal processing unit 6 or the display
unit 7 may be provided separately from the central control unit 5
that controls the engine control unit 3.
[0059] The measurement unit 60 is a means for measuring and
inputting the measurement data that are obtained from the detector
2 while the engine control unit 3 is controlled by the central
control unit 5, and testing is performed under predetermined
testing conditions, i.e., the time series data of the engine speed
N and the axial torque T.sub.d, and the time series data of the
fuel injection timing FT and the throttle travel S that are
presented from the engine control unit 3 to the engine 10 during
the same period.
[0060] The time series data of the throttle travel S and the fuel
injection timing FT may be directly inputted from the central
control unit 5, rather than from the engine control unit 3, and may
also be inputted from a throttle travel detector, a fuel injection
timing counter, or another detector that is provided to the engine
10. Besides the abovementioned time series data, time series data
of the fuel oil temperature or the intake air quantity may also be
inputted to the measurement unit 60 according to the subject of the
evaluation.
[0061] When the measurement data are made up of analog signals, the
measurement unit 60 is provided with an A/D converter to convert
the analog signals to digital signals. When the measurement data
are made up of digital signals, an A/D converter is unnecessary,
but the plurality of units of inputted measurement data must in any
case be time-synchronized with each other for processing by the
torque computation unit 64.
[0062] The memory 62 is a means for temporarily storing the
measurement data inputted to the measurement unit 60, and the data
computed by the torque computation unit 64 and the model
computation unit 66 described hereinafter.
[0063] The torque computation unit 64 is a means for calculating
the engine torque T.sub.e from the transient-state time series data
of the measured engine speed N and axial torque T.sub.d.
[0064] The relationship T.sub.e=T.sub.d-I.times.dN/dt (wherein I is
the inertial moment of the rotational axis that includes the engine
10, the transmission system from the engine 10 to the dynamometer
12, and the dynamometer 12) exists between the axial torque T.sub.d
that was measured in the past and the engine torque T.sub.e that
contributes to the actual engine driving, and this relationship
essentially indicates the simple engine unit performance. In other
words, a flywheel and other inertial components of the torque
transmission system are included in the axial torque T.sub.d and
could not be used to evaluate the true engine performance.
[0065] Therefore, the engine torque T.sub.e was calculated in the
past by measuring the axial torque T.sub.d in the steady state
(state in which the differential term of the engine speed N is
zero) during bench testing using the dynamometer 12. However, as
described above, time is required for the steady state to be
attained, and in order to shorten the measurement time, the present
invention is characterized in that the engine torque T.sub.e that
is used to evaluate the true engine performance is computed by
acquiring the transient data of the axial torque T.sub.d and the
engine speed N.
[0066] Specifically, corrected data (=I.times.dN/dt) of the engine
torque T.sub.e are calculated based on the time series data of the
measured engine speed N, the axial torque T.sub.d and the corrected
data thereof are subtracted at regular time intervals of the time
series data, and the engine torque T.sub.e (=T.sub.d-I.times.dN/dt)
is calculated.
[0067] The value used for the inertial moment I is already known
when the inertia is known in advance, but this value must be
estimated when the inertia is unknown. The inertia is estimated by
a method in which the engine or the dynamometer is driven in a
state in which the engine is connected to the dynamometer, the
engine speed N is varied from minimum to maximum to minimum, the
torque T is measured, and a model in which the torque
T=(I.times.dN/dt+a constant) is created with the engine speed N
near maximum, whereby I is estimated. The effects of temperature
are preferably taken into account during the estimation. In the
example described hereinafter, the value I=0.17 kgm.sup.2 obtained
by estimation is used for firing testing as well as for motoring
testing.
[0068] In the engine measurement device 1 of the present invention
thus configured, the measurement data (transient data) in the
non-constant transient state are used without waiting for the
engine speed N to stabilize to a steady state, the time
differential of the engine speed N is computed, and the inertial
moment I is multiplied by this time differential to obtain the
corrected data, and the corrected data are subtracted from the
axial torque T.sub.d at regular time intervals to compute the
engine torque T.sub.e. The time needed to compute the engine torque
T.sub.e is therefore significantly reduced in comparison to the
conventional technique.
[0069] The model computation unit 66 is a means for modeling the
time series data of the computed engine torque T.sub.e using the
engine speed N, the fuel injection timing FT, and other engine
parameters. Prior to modeling, first data correction processing is
preferably performed for performing time axis alignment and the
like of data that accompanies a time delay that occurs due to
filtering (noise removal), signal level alignment, and
measurement.
[0070] Modeling will be described in detail hereinafter. Specific
examples of modeling include mathematization (functional modeling),
as well as graphic representation, block diagramming, and the like,
but an example of mathematical modeling will be described
herein.
[0071] In the case of firing testing, the model computation unit 66
performs computational processing whereby the engine torque T.sub.e
is modeled into a function of the engine speed N and the fuel
injection timing FT indicated by the equation below on the basis of
the time series data of the engine speed N and fuel injection
timing FT obtained from the measurement unit 60, and the time
series data (both of which have undergone the first data correction
processing) of the engine torque T.sub.e that was previously
obtained by the torque computation unit 64.
T.sub.e=(Kf.sub.1.times.(FT).sup.2+Kf.sub.2.times.(FT))+(Km.sub.1.times.-
(N)+Km.sub.2) (wherein Kf.sub.1, Kf.sub.2, Km.sub.1, and Km.sub.2
are constants) (1)
[0072] In theory, the mechanical loss torque T.sub.m computed
during firing testing is the difference between the engine torque
T.sub.e (output) and the fuel torque T.sub.f (input), and the
mechanical loss torque T.sub.m can be generally broken down into
loss due to combustion and loss that is simply due to mechanical
components (mainly due to friction).
[0073] Specifically, the term "loss due to combustion" refers to
loss that can only be computed during firing testing, such as air
intake loss (gas exchange loss, blowdown (exhaust effusion) loss,
pump loss (exhaust, intake loss), frictional loss in the air intake
system, and valve throttling loss), loss due to incomplete
combustion (caused by the air mixture composition, air-fuel
consumption, the EGR rate, the ignition timing (injection timing),
combustion timing loss, the engine speed, and the load), and
leakage loss (caused by leakage between cylinders and pistons).
[0074] The term "loss due to mechanical components" refers to
mechanical loss (friction between cylinders and pistons/piston
rings, frictional loss from the crankshaft, camshaft, and other
bearings, frictional loss between cams and cam followers, drive
valve system loss, and pump loss) and auxiliary component loss
(caused by the water pump, oil pump, ignition device, power
steering pump, and air conditioning compressor).
[0075] In other words, the components of the computed mechanical
loss torque are different for firing testing and motoring testing,
and the loss due to mechanical components, and the pump loss and
air intake system frictional loss among the losses due to
combustion are computed as the mechanical loss torque during
motoring testing. Computation of the mechanical loss torque during
motoring testing will be described hereinafter, but for the sake of
distinction, the mechanical loss torque during firing testing will
be designated as T.sub.m, and the mechanical loss torque during
motoring testing will be designated as T.sub.mm.
[0076] Returning to the description of the present example, the
fuel torque T.sub.f is considered to be dependent on the fuel
injection timing FT, and the mechanical loss torque T.sub.m is
considered to be dependent on the engine speed N.
[0077] Accordingly, Equation (1) above modeled by the model
computation unit 66 is substituted with
T.sub.e=T.sub.f-T.sub.m(T.sub.f=Kf.sub.1.times.(FT).sup.2+Kf.sub.2.times.-
(FT), T.sub.m=-(Km.sub.1.times.(N)+Km.sub.2)). In other words, the
engine torque T.sub.e is modeled using the engine parameters,
whereby the engine torque T.sub.e is divided into a function (term
that is dependent on the engine speed N) of the engine speed N and
a function (term that is dependent on the fuel injection timing FT)
of the fuel injection timing FT, and the fuel torque T.sub.f and
mechanical loss torque T.sub.m during firing can be rapidly
calculated in the transient state rather than in the steady
state.
[0078] In the model computation unit 66, after Equation (1) is
temporarily stored in the memory 62, the term that is dependent on
the engine speed N in the model is extracted as the mechanical loss
torque T.sub.m, and the term that is dependent on the fuel
injection timing FT is extracted as the fuel torque T.sub.f, and
the terms are again stored in the memory 62 or are outputted to the
display unit 7.
[0079] The central control unit 5 feeds back the axial torque
T.sub.d and engine speed N detected from the detector 2, and since
the engine control unit 3 must be furthermore controlled so that
testing is performed under the set testing conditions, the signal
processing unit 6 of the present example also has a function
(feedback control computation function) for computing the control
signal for the engine control unit 3 and transmitting the control
signal to the central control unit 5 on the basis of the signal
inputted from the measurement unit 60. However, the feedback
control computation is not necessarily performed in the signal
processing unit 6, and the output from the detector 2 may be
directly inputted to the central control unit 5 so that feedback
control computation is performed within the central control unit
5.
[0080] The display unit 7 is a means for displaying the data
measured by the measurement unit 60, and the results of computation
by the torque computation unit 64 and the model computation unit
66. Specifically, the display unit 7 may display not only the items
of measurement data or the computation results, but also a
plurality of data function graphs, trajectories, correlation
coefficient graphs, frequency distribution tables, standard
deviation graphs, or the like. Multiple types and combinations of
measurement data or computational results may, of course, be
displayed on the same screen when the measurement data and the
computation results occur simultaneously.
[0081] In the display unit 7, the engine torque T.sub.e when the
fuel injection timing FT and the engine speed N are parameters, and
the engine mechanical loss and other related characteristics are
displayed as a graph, whereby the basic performance of the engine
10 can be visually assessed at a glance.
EXAMPLE 1
[0082] The overall operation of the engine measurement device 1
will be described hereinafter with reference to the flow diagram of
FIG. 2. An example will be described in which the mechanical loss
torque T.sub.m is calculated by the engine measurement device 1 of
the present example from the relationship between the engine torque
T.sub.e and the transient-state time series data of the fuel
injection timing FT and the engine speed N during firing testing in
which the engine 10 is combustion driven.
[0083] First, the engine measurement device 1 sets testing
conditions whereby the transient-state time series data are
obtained (S110). In the present example, the fuel injection timing
FT is increased from 0 to 30 msec through control from the central
control unit 5 and the engine control unit 3, and the engine speed
N accordingly increases from 0 to approximately 4000 rpm.
[0084] The engine measurement device 1 executes firing testing
under the abovementioned testing conditions, and the measurement
unit 60 in the signal processing unit 6 collects the axial torque
T.sub.d in the transient state and time series data of the fuel
injection timing FT and the engine speed N from the detector 2, the
engine control unit 3, or the like and stores the collected data in
the memory 62 (S120). FIG. 3 shows a graph in which the collected
time series data are shown for a period of 15 seconds from the
start of measurement.
[0085] As described above, the time series data of the axial torque
T.sub.d shown in FIG. 3 include noise components and components of
the flywheel and other transmission system inertia, and filter
processing and correction to the engine torque T.sub.e are
therefore performed by the torque computation unit 64 (S130). The
computation of the engine torque T.sub.e was performed using
T.sub.e=T.sub.d-I.times.dN/dt (wherein I=0.17 kgm.sup.2), as
described above. The graph shown in FIG. 4 is obtained by
substituting the axial torque T.sub.d in the graph of FIG. 3 with
the engine torque T.sub.e.
[0086] The model computation unit 66 forms a model so that the
engine torque T.sub.e becomes a function of the engine speed N and
the fuel injection timing FT shown in the following equation on the
basis of the time series data of the fuel injection timing FT, the
engine speed N, and the engine torque T.sub.e (S140).
[0087] The model of the engine torque T.sub.e shown in FIG. 4 is
indicated by the following equation.
Estimated engine torque
T.sub.ee(Nm)=(-0.02132.+-.0.00066).times.(FT).sup.2+(3.839.+-.0.034).time-
s.(FT)+(-0.004756.+-.0.00026).times.N+(-34.04.+-.0.39) (2)
[0088] The reason for establishing the estimated engine torque
T.sub.ee using Equation (2) is that the model in which the engine
torque T.sub.e equals the right side of Equation (2) is not
necessarily true during the entire period in which the engine
torque T.sub.e measured, and there is a period during which a
difference occurs between the actual engine torque T.sub.e and the
computational results on the right side of the equation.
[0089] Furthermore, the model computation unit 66 computes the
mechanical loss torque T.sub.m during firing on the basis of
Equation (2) (S150). Specifically, the right side of Equation (2)
is divided into terms that depend on the fuel injection timing FT
and terms that depend on the engine speed N, and is fitted to the
equation: Estimated engine torque T.sub.ee=fuel torque
T.sub.f-mechanical loss torque T.sub.m.
[0090] Equations (2-1) and (2-2) are then obtained from Equation
(2).
T.sub.f=-0.02132.times.(FT)2+3.839.times.FT (2-1)
T.sub.m=0.004756.times.N+34.04 (2-2)
[0091] FIG. 5 is a graph in which the estimated engine torque
T.sub.ee, the fuel torque T.sub.f, and the mechanical loss torque
T.sub.m calculated in this manner, and the previous fuel injection
timing FT and the engine torque T.sub.e are shown for a period of
t=5 to 20 s by the display unit 7.
[0092] FIG. 5 shows the compatibility between the engine torque
T.sub.e and the estimated engine torque T.sub.ee in a significant
time range, and it is apparent that the reliability of the computed
mechanical loss torque T.sub.m is maintained.
[0093] The display unit 7 displays graphs such as the ones shown in
FIGS. 6 and 7. FIG. 6 is a graph showing the relationship between
the engine torque T.sub.e and the fuel injection timing FT, and the
relationship between the estimated engine torque T.sub.ee and the
fuel injection timing FT for each representative engine speed N;
FIG. 7A is a graph showing the relationship between the engine
torque T.sub.e and the engine speed N, and the relationship between
the estimated engine torque T.sub.ee and the engine speed N for
each representative fuel injection timing FT; and FIG. 7B is a
graph showing the relationship between the engine speed N and the
computed mechanical loss torque T.sub.m. FIG. 7B shows the
mechanical loss torque T.sub.m computed when the engine torque
T.sub.e is 0.+-.5 Nm, but since the mechanical loss torque is
indicated as a function of the engine speed N as described above,
the value thereof is the same regardless of the value of the engine
torque T.sub.e.
[0094] It is readily apparent from the graph in FIG. 6 that there
are regions in which the engine torque T.sub.e and the estimated
engine torque T.sub.ee are negative even when fuel is injected. It
is also readily apparent from the graph in FIG. 7 that the engine
torque T.sub.e and the estimated engine torque T.sub.ee are
negative when the fuel injection timing is 10 ms or less (FIG. 7A),
and that the mechanical loss increases in substantially linear
fashion when the engine speed is increased (FIG. 7B).
[0095] FIG. 8 shows the relationship between the engine torque
T.sub.e, the engine speed N, and the fuel consumption rate
estimated on the basis of the measured/computed data thus far
(including the engine torque T.sub.e, the estimated engine torque
T.sub.ee, the fuel torque T.sub.f, and the mechanical loss torque
T.sub.m). In FIG. 8, the fuel consumption rate is calculated by
dividing the fuel injection timing FT by the engine torque T.sub.e.
It is thereby readily apparent that fuel consumption decreases as
the engine speed increases, and that the rate of reduction in fuel
consumption increases to the extent that the engine torque
increases.
[0096] In the past, since testing to calculate the mechanical loss
torque was performed without combustion-driving of the engine, it
was impossible to measure the fuel torque as an input factor, and
the mechanical loss that was calculated during combustion driving
of the engine had insufficient accuracy. However, according to the
present invention, the engine torque during firing is computed as a
separate fuel torque and a mechanical loss torque, and the engine
torque can also be computed in a short time using transient data.
The engine torque can therefore be useful for enhancing the
accuracy of ECU control for enhancing fuel consumption, and for
other aspects of engine control.
EXAMPLE 2
[0097] Another embodiment of the present invention will be
described hereinafter. The present example is of a case in which
the engine measurement device 1a is used in motoring testing. The
term "motoring testing" refers to testing in which the engine
performance is measured in a non-combustion driving state of the
engine 10 in which fuel is supplied but not combusted, i.e., a
state in which the dynamometer 12 is driven.
[0098] The differences between the engine measurement device 1 of
the previous example and the engine measurement device 1a of the
present embodiment will be cited, but other structural aspects
thereof are the same.
[0099] First, the components of the calculated mechanical loss
torque differ between the engine measurement device 1 during firing
testing and the engine measurement device 1a during motoring
testing of the present example.
[0100] Specifically, in theory, the engine torque T.sub.e of the
motoring testing is a torque obtained from the output shaft in the
non-combustion driving state of the engine 10, and the fuel torque
(input factor in firing testing) is therefore zero. In other words,
motoring testing is unable to measure the air intake loss (not
including the pump loss), the cooling loss, the loss due to
incomplete combustion, and the leak loss, which are losses due to
combustion during firing testing.
[0101] The mechanical loss torque T.sub.mm during motoring testing
is the loss other than the losses described above, and includes the
loss that is not due to combustion, such as the mechanical loss
(friction between cylinders and pistons/piston rings, frictional
loss from the crankshaft, camshaft, and other bearings, frictional
loss between cams and cam followers, drive valve system loss, and
pump loss) and auxiliary component loss (caused by the water pump,
oil pump, ignition device, power steering pump, and air
conditioning compressor).
[0102] The engine measurement device 1a is provided with the engine
control unit 3, the central control unit 5, the signal processing
unit 6, and the display unit 7 shown in FIG. 1, as well as a
dynamometer control unit (external drive means control unit) 4 that
is indicated by a dashed line in FIG. 1.
[0103] The dynamometer control unit 4 is connected to the
dynamometer 12, and is a means for variably controlling the
current/voltage applied to the dynamometer 12 during motoring
testing in the present example. The current/voltage of the
dynamometer 12 is variably controlled, whereby the dynamometer 12
is driven, and the load torque of the engine 10 that is connected
to the dynamometer 12 is controlled.
[0104] The dynamometer 12 used in the present example is a
low-inertia dynamometer, the same as in the previous example.
[0105] The engine control unit 3 also stops the supply of fuel and
provides a prescribed throttle travel to the engine 10, and the
dynamometer control unit 4 applies a current/voltage to the
dynamometer 12 to control the driving of the dynamometer 12.
Therefore, the dynamometer 12 can be considered to be an external
drive means that substitutes for the engine 10.
[0106] The engine 10 acts as the load of the dynamometer 12, the
cylinders of the engine 10 are driven at the rotational speed
obtained through the driving of the dynamometer 12, and the air
determined by the throttle travel is taken in/exhausted in the
cylinders. In other words, the engine speed N is obtained through
the control of the dynamometer 12 that is performed by the
dynamometer control unit 4.
[0107] The engine speed N during motoring testing is detected from
the detector 2, and may also be directly detected from the
dynamometer 12, or may be detected based on information (applied
voltage, current) from the dynamometer control unit 4.
[0108] The central control unit 5 of the present example controls
the engine control unit 3, the signal processing unit 6, and the
display unit 7, and is also a means for controlling the dynamometer
control unit 4.
[0109] The central control unit 5 of the present example controls
the engine control unit 3 and the dynamometer control unit 4 in the
control process of the engine 10 and the dynamometer 12 so that at
least two types of time series data that include time series data
of the engine speed N in the non-constant transient state, and the
axial torque T.sub.d that varies during the period of the transient
state are measured from the detector 2.
[0110] The structure of the signal processing unit 6 is the same as
in the previous example, but the processing of the model
computation unit 66 differs from the processing performed during
firing testing.
[0111] Specifically, the model computation unit 66 in the case of
motoring testing models the engine torque T.sub.e as a function of
the engine speed N, the air intake quantity, and other engine
parameters on the basis of the time series data of the air intake
quantity and the engine speed N (the rotational speed of the
dynamometer 12 in the case of motoring testing) obtained from the
measurement unit 60, and the time series data (which has all
undergone the first data correction processing) of the engine
torque T.sub.e obtained by the torque computation unit 64. The
function of the engine speed N indicated by the following equation
is obtained.
T.sub.e=Kmm.sub.1.times.N+Kmm.sub.2 (wherein Kmm.sub.1 and
Kmm.sub.2 are constants) (3)
[0112] As described above, in theory, the engine torque T.sub.e of
the motoring testing is a torque obtained from the output shaft in
the non-combustion driving state of the engine 10. In other words,
the fuel torque that is the input in firing testing is zero, and
the engine torque T.sub.e that contributes to engine driving when
the dynamometer 12 is driven externally is all lost. Therefore
T.sub.e can be considered equal to -T.sub.mm (mechanical loss
torque) in motoring testing.
[0113] The mechanical loss torque T.sub.mm during motoring can thus
be rapidly calculated using Equation (3) above in the transient
state rather than in the steady state. The model computation unit
66 then stores Equation (3) in the memory 62 and outputs
T.sub.e=-T.sub.mm to the display unit 7.
[0114] The mechanical loss torque T.sub.mm may be computed as a
term that depends on the engine speed N as in Equation (3), but
this configuration is not limiting, and the mechanical loss torque
T.sub.mm may also be expressed as a function of other engine
parameters to extract the separate mechanical loss due to each
engine parameter.
[0115] The central control unit 5 feeds back the axial torque
T.sub.d and engine speed N detected from the detector 2, and since
the engine control unit 3 and the dynamometer control unit 4 must
be furthermore controlled so that testing is performed under the
set testing conditions, the signal processing unit 6 of the present
example also has a function (feedback control computation function)
for computing the control signal for the engine control unit 3 and
the dynamometer control unit 4 and transmitting the control signal
to the central control unit 5 on the basis of the signal inputted
from the measurement unit 60. However, the feedback control
computation is not necessarily performed in the signal processing
unit 6, and the output from the detector 2 may be directly inputted
to the central control unit 5 so that feedback control computation
is performed within the central control unit 5.
[0116] An example of the general operation of the engine
measurement device 1a will next be described with reference to the
flow diagram in FIG. 2. In the engine measurement device 1a of the
present example, the engine 10 is not combustion driven, and the
mechanical loss torque T.sub.mm is calculated from the relationship
between the engine torque T.sub.e and the time series data in the
transient state of the engine speed N in motoring testing in which
the dynamometer 12 is driven with the throttle travel S held
constant.
[0117] The engine measurement device 1a sets testing conditions
whereby transient-state time series data can be obtained (S110). In
the present example, the fuel injection quantity of the engine 10
is set to zero, and the throttle travel S is set to 30% through
control from the central control unit 5 and the engine control unit
3, and the rotational speed of the dynamometer 12 (hereinafter the
same as the engine speed N of the engine 10) is varied from 0 to
4000 to 0 rpm at a rate of 20 rpm/s through control from the
dynamometer control unit 4. The rotational speed must be controlled
in this manner so as to later efficiently correct for the effects
of the inertia term of the torque transmission system from the time
series data of the detected axial torque T.sub.d.
[0118] The engine measurement device 1a executes motoring testing
under the testing conditions described above, and the measurement
unit 60 in the signal processing unit 6 collects the axial torque
T.sub.d in the transient state and time series data of the air
intake quantity and the engine speed N from the detector 2, the
engine control unit 3, or the like and stores the collected data in
the memory 62 (S120). FIG. 9 shows a graph in which the collected
time series data are shown for a period of 400 seconds from the
start of measurement.
[0119] As described above, the time series data of the axial torque
T.sub.d shown in FIG. 9 include noise components and inertia
components of the flywheel, pistons, crankshaft, and the like, and
filter processing (high-frequency component removal, averaging, and
the like) and correction to the engine torque T.sub.e are therefore
performed by the torque computation unit 64 (S130).
[0120] The computation of the engine torque T.sub.e was performed
using T.sub.e=T.sub.d-I.times.dN/dt as described above, but prior
to this computation, the time series data of the axial torque
T.sub.d were high-frequency analyzed and separated into a
low-frequency component and a high-frequency component, and the
high-frequency component was removed by a low-pass filter in the
torque computation unit 64 in order to remove unbalanced inertia
components (high-frequency secondary moment) due to the pistons,
the crankshaft, and other components. When the high-frequency
component that is superposed on such transient data is merely
averaged, the high-frequency component is cancelled out to zero,
the data are altered from the data that were to be used in the
original evaluation, and a proper evaluation can no longer be
performed. A method for separating the transient data into low
frequencies and high frequencies and removing unnecessary
components is therefore an essential technique for analysis and
processing of transient data.
[0121] The same filter processing as described above must be
performed for data (air intake quantity) other than the engine
torque T.sub.e. The reason for this is that a correct correlation
cannot be obtained unless processing is performed under the same
conditions when the correlation of both data sets is subsequently
examined.
[0122] FIG. 10 is a graph in which the axial torque T.sub.d and the
air intake quantity in the graph of FIG. 9 are subjected to filter
processing, and the axial torque T.sub.d is substituted with the
engine torque T.sub.e. Even after such filter processing as the
filter processing described above is performed, noise remains in
the engine torque T.sub.e in the slow portions (0 to 40 s, 360 to
400 s) of the engine speed N. What occurs near 80 s, 160 s, 240 s,
and 320 s is aliasing distortion (aliasing noise) that accompanies
low-speed sampling during AD conversion of the measurement
data.
[0123] The air intake quantity is examined before the time series
data of the engine torque T.sub.e are modeled by the model
computation unit 66. The air intake quantity is an indicator of the
pump efficiency. FIG. 11A is a graph of the air intake quantity
during the period in which the engine speed N is 2000 to 2300 rpm,
based on the graph of FIG. 10.
[0124] In the present example, the engine speed N during motoring
testing is varied from 0 to 4000 and 4000 to 0 so as to measure the
data during increasing speed and during decreasing speed to enhance
the precision of the measurement, and to examine the correlation
between the data during increasing speed and the data during
decreasing speed.
[0125] In FIG. 11A, the time axes are offset between the two data
sets (for increasing and decreasing of the engine speed N), and
since this difference occurs in conjunction with the measurement,
correction is performed by the torque computation unit 64 and the
model computation unit 66 so as to align the time axis of one data
set A with the time axis of the other data set B. The results of
performing this time axis correction are shown in FIG. 11B. The
solid line C in FIGS. 11A and 11B is the linear slope of data set A
as extended from the starting point of data set B.
[0126] As in the case of the axial torque T.sub.d, the air intake
quantity corrected as shown in FIG. 11C is divided into a
low-frequency component and a high-frequency component, and the
high-frequency component is removed by a low-pass filter. The
results are shown in FIG. 11C. The relationship between the engine
speed N and the air intake quantity per cycle of the engine 10 was
calculated based on FIG. 11C, and is shown in FIG. 11D.
[0127] It is apparent from FIGS. 11C and 11D that the air intake
quantity per cycle is unrelated to the engine speed N and
substantially constant. In other words, the engine torque T.sub.e
is not dependent on the air intake quantity in the present
example.
[0128] The engine torque T.sub.e shown in FIG. 10 is considered to
indicate the mechanical loss when combustion is not taking place in
the engine, and the pump loss that cannot be separated for
measurement, but the results in FIGS. 11C and 11D may indicate that
the engine torque T.sub.e is dependent on the engine speed N rather
than on the air intake quantity. Consequently, the model
computation unit 66 models the time series data of the engine
torque T.sub.e shown in FIG. 10 as a function of the engine speed N
to calculate the mechanical loss torque T.sub.mm (S140, S150).
[0129] FIG. 12 is a graph showing the relationship between the
engine torque T.sub.e and the engine speed N. According to FIG. 12,
a secondary approximate model of the engine-speed-dependent
mechanical loss torque T.sub.mm is indicated by the following
equation.
Mechanical loss torque
T.sub.mm(Nm)=8.49+0.000508.times.N+0.801.times.N.sup.2 (4)
[0130] A primary approximate model in the range of N=1000 to 4000
rpm is indicated by the following equation.
Mechanical loss torque T.sub.mm(Nm)=3.80+0.004653.times.N (5)
[0131] These computed models are stored in the memory 62 or
outputted to the display unit 7.
[0132] Strictly speaking, since the mechanical loss is separated
into factors that depend on engine speed, as well as factors that
depend on temperature, air, and the like, the dependent factor that
is incorporated for functional modeling of the mechanical loss can
be arbitrarily selected using a statistical indicator according to
the purpose of the testing/evaluation, and the flexibility of the
testing/evaluation increases. When present statistical indicators
are used, it is apparent that the factors that significantly affect
the mechanical loss are air intake quantity, the product of engine
speed and air intake quantity, coolant outlet temperature, and the
product of engine speed and engine speed.
[0133] FIG. 13 is a graph showing the relationship between the
engine torque T.sub.e, the coolant outlet temperature, the oil
temperature, and the exhaust temperature of the fuel gas during the
period of 163 to 198 s during motoring testing in Example 2. Since
combustion does not occur in the engine during motoring testing,
the data for the coolant outlet temperature or oil temperature are
basically unrelated to the engine evaluation, but combustion was
occurring in the engine immediately prior to the motoring testing
of the present example, and these data were therefore measured as
they naturally progressed.
[0134] FIG. 14 is a graph showing the engine torque, the engine
speed, the coolant outlet temperature, the lubricant oil
temperature, the combustion gas exhaust temperature, and the air
intake quantity at the same time as measured by the measurement
unit 60 for a period of 180 to 200 s (i.e., when the throttle
travel is 30%) when the throttle travel is varied in sequence to 0,
20, 40, 60, 80, 90, 70, 50, 30, and 10% every 20 s for a
measurement period of 200 s according to the operating pattern
shown in FIG. 16 for the purpose of forcibly varying each engine
parameter, and the engine speed at the time of each throttle travel
is varied from 0 to 5000 to 0 rpm at a rate of 500 rpm/s. When
motoring testing is performed according to such an operating
pattern, the transient data of various values can be acquired in a
short time.
[0135] FIG. 14A shows the measurement data prior to correction, and
FIG. 14B shows the results of correcting (2 Hz low-pass filter) the
pressure on the pistons or the inertia of the pistons/crankshaft,
correcting (correction using the time differential and inertial
moment of the engine speed) the flywheel/shaft inertia, correcting
(time axis adjustment for delays of 1.09 s and 0.02 s) the time
delay of the air intake quantity/engine speed occurring due to
measurement, and various other correction processing for the
measurement data in FIG. 14A. Actually, besides the data shown in
FIG. 14 when the throttle travel was 30%, all the throttle travel
data when testing was performed according to the operation pattern
shown in FIG. 16 was measured and stored in the memory 62.
[0136] FIG. 15 is a graph showing the results of analysis by the
model computation unit 66 on the basis of the measurement results
of FIG. 14 to separate the engine torque T.sub.e (mechanical loss
torque T.sub.mm) into the loss due to engine speed, the loss due to
lubricant oil temperature, the loss due to air intake quantity, and
the loss due to air movement. In other words, a coefficient
(constant) is set by the model computation unit 66 so that the
engine torque T.sub.e is indicated as a relationship of the engine
parameters of engine speed, lubricant oil temperature, and air
intake quantity, the model and the coefficients thereof are stored
in the memory 62, and the computed value of each factor is
displayed by the display unit 7. The inertial moment I used to
calculate the engine torque T.sub.e from the axial torque T.sub.d
was 0.17 kgm.sup.2.
[0137] The loss due to the air intake quantity is the loss that
occurs when air is taken into a cylinder, and is proportional to
the air intake quantity/intake air pressure. Therefore, the loss
corresponds to the factor that depends on the air intake quantity
in the created model function. The loss due to air movement is a
loss that occurs when air is taken in and exhausted, and is
proportional to the amount of moving air. Since the quantity of
moving air is indicated by (Air intake quantity.times.Engine
speed), the loss corresponds to the factor that depends on the (Air
intake quantity.times.Engine speed) in the created model
function.
EXAMPLE 3
[0138] The above descriptions were of a case in which the
mechanical loss torque T.sub.m during firing testing was calculated
using transient-state time series data, and a case in which the
breakdown (the dependent factors for each engine parameter) of the
mechanical loss torque T.sub.mm during motoring testing was
calculated.
[0139] As described above, the details of the mechanical loss
torque T.sub.m calculated during firing testing differ from the
details of the mechanical loss torque T.sub.mm calculated during
motoring testing.
[0140] First, T.sub.m represents all the loss that does not
contribute to engine driving during combustion driving of the
engine 10, but since calculating the mechanical loss during firing
testing was originally assumed to be impossible, the fact that the
mechanical loss torque T.sub.m was calculated can be considered
meaningful. Additionally, the facts that the loss (intake and
exhaust loss, cooling loss, loss due to incomplete combustion, and
other loss) due to combustion obviously cannot be calculated except
by firing testing, and that the combustion efficiency or the
exhaust gas characteristics can be analyzed from the mechanical
loss torque T.sub.m are cited as effects that are obtained by using
the engine measurement device 1 of the present invention.
[0141] Since T.sub.mm also represents the loss that does not
contribute to engine driving during non-combustion driving of the
engine 10, the abovementioned loss due to combustion is obviously
included in T.sub.mm. However, the mechanical loss other than the
abovementioned loss due to combustion can be separated into the
factor that depends on the engine speed, factors that depend on
temperature, factors that depend on air, and other dependent
factors for each engine parameter and calculated from T.sub.mm and
used to evaluate performance in engine testing.
[0142] The ability to immediately compute the mechanical loss from
the transient-state time series data is a characteristic that is
shared between T.sub.m and T.sub.mm. Another advantage of using
transient data is that the data can be used in common for engine
analysis that includes computation of mechanical loss and
computation of mechanical loss for each factor when a plurality of
items of temporally non-continuous data having different
measurement conditions is linked.
[0143] For example, FIG. 14 described above is a graph showing the
engine torque, the engine speed, the coolant outlet temperature,
the lubricant oil temperature, the combustion gas exhaust
temperature, and the air intake quantity at the same time as
measured by the measurement unit 60 for a period of 180 to 200 s
(i.e., when the throttle travel is 30%) when the throttle travel is
varied in sequence to 0, 20, 40, 60, 80, 90, 70, 50, 30, and 10%
every 20 s for a measurement period of 200 s according to the
operating pattern shown in FIG. 16 for the purpose of forcibly
varying each engine parameter, and the engine speed at the time of
each throttle travel is varied from 0 to 5000 to 0 rpm at a rate of
500 rpm/s.
[0144] The measurement conditions (in this case, the throttle
travel) may be continuously varied in this manner to measure the
time series data, but there is not necessarily a temporal
continuity between different measurement conditions, and the items
of time series data that are measured by the measurement unit 60
for each throttle travel and stored in the memory 62 may be linked
as if to have temporal continuity and used in engine analysis. When
this configuration is adopted, each item of time series data that
was stored in the memory 62 for the time being can be appropriately
linked in the signal processing unit 6 at the later convenience of
the analyzer and used in analysis, and the continuous process from
measurement to analysis is no longer necessarily needed.
[0145] FIG. 17 shows a graph in which temporally non-continuous
time series data having different measurement conditions are
linked. Separate analysis for each engine parameter of the engine
torque T.sub.e (mechanical loss torque T.sub.mm) such as is shown
in FIG. 15 is also possible from the graph of FIG. 17. Such an
analysis method is impossible in analysis of steady-state data.
[0146] Furthermore, processing for comparing the results of
modeling the mechanical loss torque T.sub.m in Example 1 with the
results of modeling the mechanical loss torque T.sub.mm in Example
2 is performed in the engine measurement devices 1, 1a of the
present invention, whereby the validity and consistency of the data
sets obtained by firing testing and motoring testing can be
verified.
[0147] Specifically, the mechanical loss torque T.sub.m during
firing testing was modeled by Equation (2-2) as
T.sub.m=0.004756.times.N+34.04, and the mechanical loss torque
T.sub.mm during motoring testing was modeled by Equation (5) as
T.sub.mm=3.80+0.004653.times.N. When these models are compared, it
is apparent that the dependent coefficients of the engine speed N
for the models are 0.004653 and 0.004756, and are quite
similar.
[0148] In other words, the mechanical loss models obtained by
different testing methods using the engine measurement devices 1,
1a of the present invention are valid, and there is consistency
between the mechanical loss torque T.sub.m and the mechanical loss
torque T.sub.mm, which have different component factors.
[0149] Since T.sub.m and T.sub.mm can be treated as data in the
same dimension, different mechanical loss data resulting from
different tests can be appropriately combined and used for engine
analysis. For example, it is possible to calculate only the loss
due to combustion within T.sub.m by subtracting T.sub.mm from
T.sub.m. This result could not be calculated in the past from the
results of the independent firing testing and motoring testing.
[0150] Not only is the mechanical loss during firing testing
calculated, and separate computation of the mechanical loss for
each engine parameter during motoring testing performed rapidly
using the transient-state time series data, but the ability to
combine the different test results of firing testing and motoring
testing makes it possible to fully anticipate contribution to the
development of an engine/ECU that is adapted to the future
low-energy age.
[0151] As described above regarding the examples of the engine
measurement device, the engine measurement device of the present
invention is not limited to an engine measurement device that is
provided with all of the structural requirements described in the
examples above, and various changes and modifications are possible.
Such changes and modifications are also, of course, encompassed by
the range of the claims of the present invention. For example, the
engine measurement devices 1, 1a may be formed separate from each
other, or may be configured as a single device (single system) in
which the functions of each are combined, and firing testing and
motoring testing can be appropriately selected.
[0152] It is also apparent that the torque computation unit 64 and
the model computation unit 66 may include, for example, a noise
remover (filter) for removing data noise (including components that
are not needed for evaluating engine performance), an arithmetic
unit, a calculus unit, an averaging computation unit, a standard
deviation computation unit, a unit for measuring data frequency or
the like (counter), an approximate expression computer, a
frequency/delay time/correlation coefficient analyzer (FFT, impulse
response, cross-spectral), and other publicly known computation
units. These publicly known computation units may be included in
the signal processing unit 6, and the torque computation unit 64
and the model computation unit 66 may be configured so as to call
for computational processing by these computation units as needed.
When the signal processing unit 6 itself is composed of a
computation device, the abovementioned primary data correction
processing or the check processing and other processing performed
prior to modeling may be performed within the signal processing
unit 6, and may not necessarily be performed by the torque
computation unit 64 or the model computation unit 66.
BRIEF DESCRIPTION OF THE DRAWINGS
[0153] FIG. 1 is a diagram showing the structure of the engine
measurement device;
[0154] FIG. 2 is a flow diagram showing the general operation of
the engine measurement device;
[0155] FIG. 3 is a graph showing the relationship between the axial
torque, the fuel injection timing, and the engine speed during
firing testing;
[0156] FIG. 4 is a graph showing the relationship between the
engine torque, the fuel injection timing, and the engine speed
during firing testing;
[0157] FIG. 5 is a graph showing the relationship between the
engine torque, the estimated engine torque, the fuel injection
timing, the fuel torque and the mechanical loss torque during
firing testing;
[0158] FIG. 6 is a graph showing the relationship between the
engine torque and the fuel injection timing, and the relationship
between the estimated engine torque and the fuel injection timing
for each engine speed;
[0159] FIG. 7 is a graph showing the relationship between the
engine torque, the mechanical loss torque, and the engine speed,
and the relationship between the estimated engine torque, the
mechanical loss torque, and the engine speed for each fuel
injection timing;
[0160] FIG. 8 is a graph showing the relationship between the
estimated fuel consumption rate, the engine speed, and the
estimated engine torque;
[0161] FIG. 9 is graph showing the relationship between the axial
torque, the engine speed, and the air intake quantity during
motoring testing;
[0162] FIG. 10 is a graph showing the relationship between the
engine torque, the engine speed, and the air intake quantity during
motoring testing;
[0163] FIG. 11 is a graph showing the relationship between the
engine speed and the air intake quantity;
[0164] FIG. 12 is a graph showing the relationship between the
engine torque and the engine speed;
[0165] FIG. 13 is a graph showing the relationship between the
engine torque, the coolant outlet temperature, the oil temperature,
and the combustion gas exhaust temperature during motoring
testing;
[0166] FIG. 14 is a graph showing the engine torque, the engine
speed, the coolant outlet temperature, the lubricant oil
temperature, the combustion gas exhaust temperature, and the intake
air quantity during the period when the throttle travel is 30% when
the throttle travel and the engine speed are varied during motoring
testing;
[0167] FIG. 15 is a graph showing the results of analysis to
separate the engine torque (mechanical loss) into the loss due to
engine speed, the loss due to lubricant oil temperature, the loss
due to air intake quantity, and the loss due to air movement;
[0168] FIG. 16 is a graph showing the operating pattern of the
motoring testing performed in order to obtain the measurement data
that are shown in FIG. 15;
[0169] FIG. 17 is a graph in which temporally non-continuous time
series data having different measurement conditions are linked.
DESCRIPTION OF THE NUMERICAL SYMBOLS
[0170] 1, 1a: engine measurement device [0171] 10: engine [0172]
12: dynamometer [0173] 14: stand [0174] 16: torque transmission
shaft [0175] 16a: universal joint [0176] 2: detector [0177] 3:
engine control unit [0178] 4: dynamometer control unit [0179] 5:
central control unit [0180] 6: signal processing unit [0181] 60:
measurement unit [0182] 62: memory [0183] 64: torque computation
unit [0184] 66: model computation unit [0185] 7: display unit
* * * * *